Effects Of Root Growth Of Vallisneria Natans On The Black And Odorous Water

Black and odorous water is an extreme phenomenon of water pollution,and the phenomenon of black and odorous water is very common in China, so the management of black and odorous water is not urgent. However, the use of submerged plants to reduce the degree of water blackness is too simple, and black and odorous sediments for the plant roots of the impact of high nutrient content will lead to plant roots cannot grow, or even plant rot or death, so how to improve the viability of submerged macrophytes has become the focus of research on phytoremediation of polluted water. In this paper, the effects of adding oxidants and accelerators on the growth of Vallisneria natans ( V. natans) were studied by outdoor simulation test, and the effects of their combined effects on the blacking effect of V. natans on water were studied. This experiment sets up a total of five groups, namely control group,V. natans group, V. natans + oxidant group, V. natans + stimulant group and V. natans + oxidant + stimulant group, with 4 replications per group. A 30-day trial, through the analysis of the data of sediment and overlying water and biomass, obtained the following conclusions:1. Planting V. natans, adding oxidant and bio-stimulanthas a significant function for the content decrease of C, N, P in the sediment (P<0.01),also can promote digestion for each layer of organic matter in the sediment, and has also played the role of ascension for oxidation-reduction potential, obviously improve the oxidation-reduction potential in the sediment, which effectively explains the sediment content in black and odorous water can be effectively reduced by plant roots and oxidant and stimulant.2. The test results show that planting V. natans, oxidant and bio-stimulanthas inhibition to the TP, TDP in the overlying water(P<0.01).and significantly increased the DO's content and the transparency of the water in the overlying water; planting V. natans and adding bio-stimulant to the overlying water has obvious inhibitory effect to the TN and TDN (P<0.01); in the experimental group which was added oxidant the content of TN, TDN, NH4+ was increased first and then decreased, but after was lower than that of the control group (P>0.05).3. With the increase of root number, root width and root cone, the oxygen content of root increased.4. Through the injection of oxidant and bio-stimulantsto the sediment,the biomass of V. natans was increased to a certain extent (P>0.05).The oxidant is calcium nitrate which contains N that leads to the content of N in the V natans + oxidant group and V. natans + oxidant+ stimulant was more than other experimental groups. Because the bio-stimulantscan increase the growth of microbial activity in the sediment, the microbial activity in sediments can provide the necessary growth environment for plants and promote the growth and development of plants to some degree.